SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '93da6a0e6bf027949891e64326f459894dd1a48bf226a53af8728348b22f1d03' 
  AND token = 'I8UYcXhzk4MCiKFs2OQLDlB/eg4YgZmkqOsovNcIY/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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