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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f39baf75d0b9c33ee3b330d0802de687f6205bb1db0df1b50df007e5fcbd6a05' 
  AND token = 'TVKFbwLo2U0uBvZFyQN6bjVQ1hBDV8QMR+gKOT4L8eU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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