SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5205199d7e4481793e2e9afed53e0195039982e3cd2c968da737480191832b11' 
  AND token = 'LMGsjpGxJ2mNW0Dz8wx7iExZTXdBaDIDQUeg+DbY4xU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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