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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d4a534e96648c88dff8807aead462b2e8d0d02236d1f50f9baca9d7472dba66' 
  AND token = 'FH5+Ee7Py7ibq8cHr2GKt7Arlk5MKpjmqKNBB2GrNOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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