SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb4d6069f18a58e5df0c5c7ff39d48e39afdebbc6c1720dbce52b05c2ea3ca23' 
  AND token = 'jl2//IO+BOIBjqcOF+YkGVLg899ptjvPAMVb+3CbqZk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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