SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd15d7fd3ac30680da03d2e3274acef88768f3f96bd71aa668a7e47a13dd11fc2' 
  AND token = 'FlS2eAjzqL6HerhLQZDFc+KsS7rbAGUtlArfcnDAQHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}