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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b42e6ec7689ab2479f2097f2079fb951573e3b1f954b061e5b66cf34b90695f4' 
  AND token = 'wFoHvRSAnW4s2TkW1ZuIO2rmFQ8VCTOAYBbFsRhUVo0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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