SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b1f1d8adc4aa4e7bd9850781168d10080660dc1390e35aabd788d46448e96a0' 
  AND token = 'xxpKzNQQv5VmbH+NWE6UYli3ELZOrlm3AzQfOou3zdg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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