SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4db5f6d797b7d3152b8e0628173a367eb0e7fa0594c5ef15927017ca3e67ff2b' 
  AND token = 'smBqO2x8ueD/wuidCG6EZFsz3CnTvgloWR+vSEQoyN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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