SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2758031005e52331b710204b129624086c1b15dbe840a365de4b44734231c09' 
  AND token = 'dNGDQS/R9VGnluEECGvRpUSswijn74YqZFdz0DocfGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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