SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a591b7e598548b19cc4b1f70ec8ae146fc765496dc87d16945b7dde9803c85d' 
  AND token = 'wlNtU4A1EbyE7qH5erk1pSMHB3bILCT9K3bYsUJrHO0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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