SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '267c6c5ae0ab2be5610f6e976a7cbadab99bf31b95d49cbc75663aefd291a78a' 
  AND token = 'LyjgSRT0d+4UJwNkocYCnxlso4Sps0D64FaUHrBPV8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}