SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ab7678a661a85dcddea1937583d0fa65de426963f932468f7a69541a9d216da' 
  AND token = 'ovSggnInph3lWFAlVKQStEb0+q2cy/Tc7nqnb+P2FD0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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