SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2cee365b2426ed81259b2daafb397b9f9b36acddf2631e4a8072b26753c2a01' 
  AND token = 'fV7Sh4QcsXKgfSASHtmA6NTExMAtdEnLUHElChbOAoM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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