SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '910e7361a0f31f54affb7f667da6e95983527bdd3f4b9644af81b2a1e559cc79' 
  AND token = '6iX08yzTWkf4/nhVkwcZSC5mBLcwVwyn7DGri3TLjrc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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