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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd1d7dac3c96e78b2a2499d55d0ad2bb0ef86d292cf76653dc7031020a9b4be32' 
  AND token = 'MnELbKZNOYfLOJY6uS4IyDfc/kkyMMVhbpvgvEYdCr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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