SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df1e9b0620430eb78364d02131f0865922e5979ac43ac015cd2fa36042008938' 
  AND token = 'Ml8Y+nOTXvUDCtEaBOj1lnM4XQs+4yUruc5CL6fgCl8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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