SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e90bfa698add4dda5ccf5c482e7b4813ac43c992177d8fc4007ecb503215be6' 
  AND token = '1r1tcsG9xBmXYLW1DgZUGxYEy6HgUumbzzceRBMCic4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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