SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '610ec68ca219d01a7cc2414822970d50db31989e09383fa4b41a81558fd202fa' 
  AND token = 'srwmopZLBI6qKGoYY87g2DXED7CCcaTBcIz245rTmuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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