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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '84db596d53202799f7fbf7edefd8c399198fd455afbce04ed7aec06251498de7' 
  AND token = 'b66aI3Vs3llVC+lH7xCsXrtZ44hQshoK6fdHK4qt0Dg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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