SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66e21abae14c8d3f7f0cb844b366cff1b6e4ce5c2c73e07315aa2568d8491f8f' 
  AND token = 'E0PIt6V1b607iWKtm2lXvrCpwDTzgpsFhPvMg4BtGwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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