SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '307a805e8f6dc9ed140a6d0c55975d8702dc3ca503c500e83df5953b305ed281' 
  AND token = 'vgYPrJjm2uwqTFxEDy2W8bsrrlQwZ8U2nSlF2o+QBbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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