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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c6cf01cd31022ccf43ab9cc9144c8188da31dca40270e478f8e4fee6ec4e8a' 
  AND token = '6x4YinN3ccfIz/PmDgjO+XP/DTdI2Ot4qGFOUj6P7Ng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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