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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b82efabc7de7b8040888d4d5bc0ee20eed8db48fa747aad01507b0b9cf70556c' 
  AND token = 'f0aRW7dI8h72k7VN7KWsIkE5pyCLvbLVNmeFgwc74P0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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