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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b6e5dab734c65ef754ccfd10cc0abe1390fa0c4d5375918e21edfc43a9d5ea6' 
  AND token = 'KMwTL/Axx/5iWq4f2FPbwUDsx0FdMKwT6eI6OXKaSQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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