SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '782e6ac9cf34360c8edc4cc479ced1315b0bcac0cb25d0cbb3b0ddc0a653f656' 
  AND token = 'FMzfbLMUSHrP6i+dvB6TXHKOFrHkrGsggbPehiM5ZQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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