SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c3c1d759b862ef95f366d108a59af5a1276ac714a22a3c278dcc8ccc6e140a0a' 
  AND token = 'PhACUWqRFLTJwmevm+OMeFGrUNin6Fq/sBnskG5QBII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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