SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a4b489ebfde7cfc4591928dda099c7c5b23db24c39574f26f849bce7af46204' 
  AND token = 'myIRDMdL8x00DmBkyAIq+DbfKOTnksZdAQRnMRuxszY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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