SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6870ff7e07294489096a6b9feba6b7b31c95a8aaf748a04077f1dd9775730423' 
  AND token = 'msvHEK1ahvICb3Z5vxWOKSLSEp+PKqPrkGohyzNpVY4=' 
  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"
    }
  }
}