SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e3eff791d281bf7645a71978f8e605c748ce3f9248272e46732db83a10e5bcc' 
  AND token = 'ruuVQvyvb5qJgN3RmroFT2og4I7/GCQQPDAKiBlkjJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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