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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd5dd52f62d5bc2206e934d3343ce4f4ada0ff348d28a22ef7885b9a8d65bd71b' 
  AND token = 'JqjWbgMtigSY82aauF+GSK4rsUPVAYJusOEiZjiDkKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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