SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c18ba766d4d1f4052b55ef993e13f190e3183e2c6c5427cf13941723d7d8b898' 
  AND token = '1FzXSt6OsFASliBbcWc9Zx3lbzCzG++O/6iDfJTZp8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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