SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7842ce183eda3d9155333fc36c389158015bc6cb2519477683e9ecae462091fe' 
  AND token = 'C0afob94ytI3igq2URCWmuGkunWSrEDBXXPt4TWq3Yk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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