SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '677fc39ff4458c3390fe3956fbe0b86ddda0c6f2fcd7eb7c9267b7d12700ddc6' 
  AND token = 'nhdmvWYv9VA3gDt6bClLGaYrSIMGei6QIZQ4a56j7Hk=' 
  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"
    }
  }
}