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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fc1d0710beaee0aaba0b08bb50c05262da5f4ecf5a6a2e9567b8e9d985c1b14' 
  AND token = 'vEUDb6HXez+sT1kV+LUKuRZPWcj1CxDa4sh6byam/KQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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