SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ae72afc0d5c5bef8988a9f68d162ad6b43619498f84117205df4965bdde6256' 
  AND token = '2MsohmHVf0RMgUp4Rs7h7Qzk2lBBTnTv/uOE2znijfo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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