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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4e709c43227f3045ed621b44713517ccbe4a2e8b354d5fb112696ddc1a88ac8' 
  AND token = 'mVfV+dY87v/Br+Ax3Xz5tqjizrapk8VdmgT+d5pHEVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}