SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e83fbef76876fc420f2076b00fcec3a7ec85f1bcc6e5a65eb33cbe9b13720983' 
  AND token = 'OAErFm7puPxu1BBKOxDWRCRe96Amwb3gwTLnb4+ebR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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