SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1b350a0304202c2151b957597d414898883d521ff2bcbec8a663680d68e84f1' 
  AND token = '6HJuTPYPvAj0ryX77Y/Y17wpr9NCHSqjVZwOUmvSR3c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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