SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3aacef112aa0b37a23e436941da2b7185e53ca3beba6acb2b6c051582fac901a' 
  AND token = 'rcBNxgOxVjNQxSKwHQvrydMzoUQXXLYySL4jg3Jq+ks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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