SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6910d5381f426228871ca486384085a290b39ff7bd33a153c70b14b0cb0ffbaa' 
  AND token = 'K4cfE4XreNc0gv3zuUQ3dMoVAjy14Ecx+/NHS6/v8NY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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