SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75adbdd2a9237cebb31c508682fcfe792102de5fd8b25b7913246a895525534f' 
  AND token = '4XndCWi3cXzKYkKGYd8IJFkACSq+gpNkyN6/VmBaoSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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