SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b034fd1c0a9593609bd809f76019173881264bceb8d65f168e9a12bf4608c003' 
  AND token = 'yMlLXSqnItcx2uEZ6XaRfgrHtg822KcSMmXC+3aAWk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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