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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a28cfcbfed40d34208f9d037a53e1489c5d6238f5d230d673a4e5e67168a87c3' 
  AND token = 'v7rEWUIbtdrvAf/ehEM2+H1DDgsgU/wiQpyXlNvb/oQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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