SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b8cfe7b26497b3b5fbf511a22aca2e2892825a296981599e8360f74439d6e43' 
  AND token = 'DzGUcq3IcNALYGKncWfF/kSVVfOKppYnMfaLAvywYx0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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