SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44827817c669a65521a7575896ee9847cc7aba4fcd634a444d2c30c182afda2f' 
  AND token = 'cp0ozUiJeNjMCv+5g0ekAEVa33rpfGNZdsZcg0GRLdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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