SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'e51d4262876c7ebb521f5214b1cd2da09287b41c9387762942ff881f9b9aec45' 
  AND token = 'gTkjDkF/bf2YNCI1i6EVjCo+/LAVNUvC9UfqMbtMHLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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