SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b36a11aae5a0724f7d49b0384054374b70e4c5d3575d33006f2a4e80d8677d1' 
  AND token = '/oOPPs7rBBsYhHtYQOJ4mLejXSkVzWKpM7rI0a4p4V0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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