SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '547aa53f82322de244c01af07c4509ac6684ffe7cb9d995ac5f6891d3471a187' 
  AND token = 'V0UN4oB1CT79b/vIjhYnY9DvmjL2cJjvFYh/zyKTeac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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