SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8753f8fecdc5b61943c3c296a257a92954048dd8fd87e43b3e171cef757900bc' 
  AND token = 'rNUxM1VU22y/xS1DJ88GsmFTJLdCd8dxvwzZ/VVMpDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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