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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2f4120e2fc4ef3b5136c7d07ebda35614bea40b18a47c653d374b26f4a947a4' 
  AND token = 'Nq6h2pDPZQL8HRmlAp2tZuoN/cLwDfqLfk2DPeLm/QQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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