SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'babe906a6bda4883c6823868e363de9acd42e1ec2b57e907746383ae89d1de31' 
  AND token = 'fXrjEPaalLIjjBUJ+Gt+9rtcDA9GE0P+XZfZ7RZoTmY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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