SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0319ce597998688373927e1896868c23800c667004b155590681547b4b99056' 
  AND token = 'UfBI7V3SQDzawb3QS+26/ixw4jekQ3Pheh7NCF2GxCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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