SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '766b6c18986f00dc12cc734b04142846c42671dfc8e1e9eb82dd69412d460bb9' 
  AND token = 'Xsih3Vh6ULPGanI2it4x1qzRRm+h/BboRsvRHptGBUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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