SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c189344dcb07452f75d09b01f62dffcc63a5546c5a8997296eeb0c145725b8a7' 
  AND token = 'VZXnZ3Ry1X5YFN9pW8Viw3CN0/f8XcxCpRIBTxv7NLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}