SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81ebfdf7d9cdf51cc6daaab77a98627de7ed250432ec5a308a7e7270bf7b95bc' 
  AND token = 'h9yTmOdJv47eyITwnstizNsaIc+npkfmG1551QNBYrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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