SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '639c7760633ef1a70e14238ee8b015d2850ed0357fdb75ab7a5930e6224a7f9a' 
  AND token = '2JbIACGeJKZg67s9llbtRXzJflFbFq+1W7bJ7kOEggA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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