SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb9ecb7d86ddbcdf2b9b6f94f5917904cb1404f31898b872a2813d17644915aa' 
  AND token = 'EFd5PA4+NZV0QPzBG+BGTKY3Jh7qsuLBiLtdnM1v2MU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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