SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08a73ecfa56e3020263b32c1959a846b4ce1c28552fba03663c8e05bab304442' 
  AND token = 'u4U0t8xwMOw5niXqaevgtpZmbQeO4wkiEGznTldJcHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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