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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d02efde77733ce9a1cd6655eb6eacc3d2af4cdabf0e130e4ca730b5603f3d50' 
  AND token = 'S5YKRL9ZUMm9ACkCfq9L/ZfJdzAUWIVS9JbHskFDb5E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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