SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '575ca8dcf3f86439430a9ad328e784cd34ade2d5fc2b51e175b8addf903329ce' 
  AND token = 'SYoUtcICSTINRCZvXiS5jCLSVHKBfrF2VngEYefqneU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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