SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd351c7636a4c6feeec63eb4ac0a0a243f1625dcb3418b45fde2119a06949f559' 
  AND token = 'JPlrWZ2g8dg/8VPAEvkCrpb/w6j+9zwNF1bgPMSvQX0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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